This paper presents a model to capture the electromechanical dynamics of a wind turbine with hydrostatic transmission (HST) coupled to the electrical grid through a synchronous generator. The HST is a continuously variable transmission that decouples the generator from the wind-turbine rotor shaft, which allows it to rotate at its synchronous speed. The topology does not include any power-electronics interfaces for energy conversion. The dynamic model of the HST and synchronous generator are used to examine the performance of the system under various disturbances in incident wind through detailed time-domain simulations. We find that with the proposed topology, the terminal voltage and frequency of the generator can be well regulated under a variety of large-signal disturbances.